Electronic devices containing active organic materials are attracting increasing attention for use in devices such as organic light emitting diodes (OLEDs), organic photoresponsive devices (in particular organic photovoltaic devices and organic photosensors), organic transistors and memory array devices. Devices containing active organic materials offer benefits such as low weight, low power consumption and flexibility. Moreover, use of soluble organic materials allows use of solution processing in device manufacture, for example inkjet printing or spin-coating.
An OLED may comprise a substrate carrying an anode, a cathode and one or more organic light-emitting layers between the anode and cathode.
Holes are injected into the device through the anode and electrons are injected through the cathode during operation of the device. Holes in the highest occupied molecular orbital (HOMO) and electrons in the lowest unoccupied molecular orbital (LUMO) of a light-emitting material combine to form an exciton that releases its energy as light.
A light emitting layer may comprise a semiconducting host material and a light-emitting dopant wherein energy is transferred from the host material to the light-emitting dopant. For example, J. Appl. Phys. 65, 3610, 1989 discloses a host material doped with a fluorescent light-emitting dopant (that is, a light-emitting material in which light is emitted via decay of a singlet exciton).
Phosphorescent dopants are also known (that is, a light-emitting dopant in which light is emitted via decay of a triplet exciton).
A hole-transporting layer may be provided between the anode and the light-emitting layer.
“Synthesis and Application of Photolithographically Patternable Deep Blue Emitting Poly(3,6-Dimethoxy-9,9-dialkylsilafluorene)s” Applied Materials & Interfaces (2014), 6(1), 83-93 discloses formation of a patterned light-emitting layer by depositing a blue-emitting poly(silafluorene) and reacting norbornene substituents of the polymer by photolithography.
KR 2009/093144 discloses polymerisation of a norbornene monomer substituted with a triarylamine group.
Chemistry of Materials (2007), 19(23), 5602-5608 discloses norbornene-based copolymers with iridium complexes and bis (carbazolyl) fluorene groups in their side-chains and their use in light-emitting diodes.
WO 2013/005026 discloses hole-transporting polymers substituted with benzocyclobutene groups. Use of these polymers as the hole-transporting layer of an OLED is disclosed. The benzocyclobutene groups are crosslinked to render the layer insoluble. The benzocyclobutene groups may be reacted with each other or may be reacted with a double bond group.
It is an object of the invention to improve performance of organic electronic devices, in particular organic light-emitting devices, in which one or more layers of the device is formed by deposition of a semiconducting layer of the device by a solution deposition method.